The Euripides Koutlidis Foundation and Collection are jointly housed and operate together with the National Gallery – Alexandros Soutsos Museum, following an agreement ratified by the Athens Court of Appeal. Artworks in the Koutlidis Collection are on display in the permanent display of the National Gallery – Alexandros Soutsos Museum Collections.

Merger of the Christos & Souli Kapralos Foundation

After the merger of the Christos & Souli Kapralos Foundation with the National Gallery – Alexandros Soutsos Museum, the foundation's estate became part of the National Gallery. It comprises some 5,000 works by Christos Kapralos: sculptures in wood, bronze, marble, stone, paintings, microsculptures, terracottas, drawings, pottery, and more. The sculptor’s studio on Aegina also came into the National Gallery, and today serves as the museum’s annexe; similarly, an adjacent plot of land will host the new Christos Kapralos Museum. The studies were performed by architects George Parmenides, Professor, NTUA, and Christine Longuépée. The project is funded by the Attica Region and is currently in the bidding stage.